In manufacturing of an electronic device, plasma etching is performed with respect to a layer to be etched of a workpiece. In the plasma etching, it is required to uniformly etch the layer to be etched in a plane, that is, in-plane uniformity is required.
As a method of realizing the in-plane uniformity in the plasma etching, an atomic layer etching method in which the layer to be etched is etched in an atomic layer level, that is, an ALE method is known. In the ALE method, a step (hereinafter, referred to as “first step”) of adsorbing an etchant generated from a first processing gas to the layer to be etched is performed in a processing container of a plasma processing apparatus. Subsequently, a step (hereinafter, referred to as “second step”) of substituting the gas in the processing container, that is, the first processing gas with a second processing gas. Subsequently, a step (hereinafter, referred to as “third step”) of generating a plasma of the second processing gas and of drawing ions into the layer to be etched is performed. Subsequently, a step (hereinafter, referred to as “fourth step” of substituting the gas in the processing container, that is, the second processing gas with the first processing gas is performed. In the ALE method, a sequence including the first to fourth steps is repetitively performed. Such an ALE method is described, for example, in Japanese Patent Application Laid-Open Publication No. H3-263827.